Not to beat the proverbial dead horse here but I thought I would point out one such situation where we do a regular shrink of database files. I am sure there will be more than a few disagreements to this but it works for us all the same.

We have a database that normally runs in the range of about 100 GB and it stays that way most of the month. Once a month however they run a process that increases the size to nearly a TB. Now I know what you are thinking it must be a poorly designed process but this process is for a Power Substation and it pulls in data from something like 90 different servers and runs some calculations that when I tried to understand them frankly made me feel slightly insecure about myself.

Now my belief with this situation is the DB is used 24/7/365 and I want to minimize impact. So after the process I reduce the size thus reducing the amount time it takes to run a full backup and other tasks. I am sure many will disagree but alas I do what works for the situation.